The pathologic analysis and molecular characterization of human tissue samples is a fundamental and integral requirement for all portions of this SPORE application, including systematic pathologic evaluation of micrometastatic disease, collection and analysis of human tissue samples for oncogenomics and gene discovery, evaluation of genetically engineered mouse neoplasms with moleclular imaging correlates, analysis of cancer signaling pathways, and characterization of tumoral heterogeneity in the emergence of chemoresistance. The core is highly integrated with each of the 5 major projects. We will work in close collaboration with the Project Investigators for three specific purposes: i) to provide tissue specimens, histology services and standardized systematic morphologic consultative expertise in the pathologic evaluation of human gastrointestinal neoplasms; ii) to provide infrastructure and technical expertise for a variety of molecular pathologic assays, including high-efficiency screening and validation of genomic and proteomic targets in human gastrointestinal tissue specimens; and iii) to evaluate and implement new cellular imaging and analysis technologies that will greatly facilitate these research goals in future. Centralization of these Core activities builds upon the established infrastructure and intellectual expertise of the investigators, and provides a highly valuable component to the analysis of biological resources developed and utilized by project investigators. In addition, the core has strong integrations with the Biostatistics Core and Genomic Data and Bioinformatics Cores (Cores 3 and 4), thereby leveraging the greatest benefits from these resources, and providing a wealth of opportunities for significant advances in understanding of gastrointestinal carcinogenesis. Our specific aims are as follows: (1) to provide tissue specimens, histologic processing services and pathologic analysis of human gastrointstinal neoplasms; (2) to characterize human gastrointestinal neoplasms using molecular pathology tools; (3) evaluate and implement new technologies for cellular imaging and molecular characterization.